The invention concerns a photographic plotting process and an arrangement for tracing a computer-stored grid image on a flat photosensitive carrier. Photographic plotting processes and arrangements are used, among other things, for manufacturing photographic patterns for printed circuit boards. According to the current state of the art, a number of different processes and arrangements are already known.
The invention described in this document is most similar to the photographic plotting process described in the German patent application 10 2007 051 990.9-31 and the arrangement for tracing a computer-stored grid image on a flat photosensitive carrier is most similar to the arrangement described in this patent application 10 2007 051 990.9-31.
According to this German patent application 10 2007 051 990.9-31 the grid image T (overall image) is traced dot by dot by a computer program as a series of partial images on an image carrier moving in direction y through an exposure station. All the image dots of a partial image are traced simultaneously.
The partial images are traced at each moment a flash takes place and at which the tracing carrier has moved forward by an equal distance. The amount of this distance corresponds to the length of a side of an image dot or a multiple thereof.
Successive partial images overlap one another partially. The partial images always coincide exactly with a section of the overall image being traced. The image is traced by a light-controlling unit, preferably a semiconductor chip with tilting mirror elements with light-controlling elements arranged in the form of a matrix. In order to trace each partial image, a computer program loads the light-controlling unit with a corresponding control pattern. When the light-controlling unit is exposed to the flash, each light-controlling element conducts a beam of light (as dictated by the pattern) to the image-dot grid position assigned to it on the tracing carrier in order to create the desired image dot. This process of image tracing is used predominantly for making photographic patterns for printed circuit boards, the direct exposure of circuit-board material etc. and manufacturing three-dimensional structures for optical elements.
The resolution of such an image-tracing process is limited to the size of the image dot. The purpose of the invention is therefore to describe a photo-plotting process and an arrangement for executing it in order to obtain a higher image resolution.